1. Field of the Invention
The present invention relates generally to a process for manufacturing a reinforced float glass, and more particularly, to a process for manufacturing a reinforced float glass by inserting a metal reinforcement, such as a linear metal wire or a metal wire web, in a continuous float glass ribbon.
2. Description of the Prior Art
In the industrial manufacture of a reinforced glass ribbon, two processes are generally employed. In one of these processes a molten glass is formed in a ribbon between a pair of forming rolls and a metal wire, either a linear wire or woven metal wire, is inserted into the molten glass ribbon from the rear part of the forming rolls. The other process is the so-called "sandwich process," wherein a metal wire is fed at a boding position in the step of sandwiching it between two glass ribbons by a pair of pressing rolls. In the reinforced glass manufactured by these processes, the glass surface is formed by contacting with the forming rolls, whereby the smoothness of the reinforced glass is obliged to be deteriorated. Accordingly, the glass reinforced with a metal wire is manufactured as a patterned glass wherein smoothness, flatness or parallelism can be ignored. In the manufacture of a transparent product, the patterned glass reinforced with a metal wire is polished to provide a smooth surface.
Certain processes for manufacturing glass ribbons reinforced with a metal wire which have excellent smoothness, flatness and parallelism, utilizing a float process, have been proposed. In accordance with these processes, continuous glass ribbons, in which a metal wire is inserted, are moved along the surface of a float bath, that is a molten metal bath, protected by a non-oxidizing atmosphere, whereby the surface is fire-polished to impart a finished surface as those of polished plate glasses. However, in the fire-polishing step, in order to improve smoothness of the surface of the glass ribbon, the temperature of the float bath and the time of contacting the glass ribbon with the bath are increased over certain predetermined ones so as to decrease the viscosity of the glass ribbon. As a result, a metal wire having relatively higher specific gravity than that of the glass is sedimented into the glass ribbon. Accordingly, concave parts corresponding to the metal wire are formed on the upper surface of the glass ribbon and convex parts corresponding to the metal wire are formed on the lower surface of the glass ribbon. When a glass (specific gravity of 2.5) having a thickness of about 7 mm inserting a steel wire (specific gravity of 7.9) having a diameter of 0.5 mm at the central part is floated on a molten metal bath at 950.degree. C for 10 minutes, concave parts having a depth of about 10-20.mu. are formed on the upper surface of the glass and convex parts having a height of about 10-20.mu. are formed on the lower surface of the glass.